Miniaturized diaphragm pump with non-resilient seals

ABSTRACT

A diaphragm pump head with a non-resilient seal comprising: a valve head and a mating valve cover forming a diaphragm chamber. A pump diaphragm forming at least a part of a wall of the diaphragm chamber with the valve cover including an inlet passage leading from a pump input port and through an inlet valve to the diaphragm chamber, and an outlet passage leading from the diaphragm chamber and through an outlet valve to a pump outlet port. The inlet valve and the outlet valve each include a valve diaphragm, and an inlet non-resilient seal and an outlet non-resilient seal. Each non-resilient seal including first and second annular diaphragm seating faces formed in mating faces of the valve body and the valve cover surrounding the inlet passage and the outlet passage and a non-resilient, deformable valve diaphragm entrapped between the first and second diaphragm seating faces.

This application claims priority from U.S. Provisional Patent Application No. 60/684,896 filed May 26, 2005.

FIELD OF THE INVENTION

The present invention is related to a miniaturized pump and, in particular, to a miniaturized diaphragm pump with non-resilient seals.

BACKGROUND OF THE INVENTION

Small diaphragm pumps are commonly used in a variety of different applications requiring, for example, the movement of gases or fluids or a supply of air or suction at moderate pressures, flow rates, etc. Typical applications could include, for example, medical, chemical and biological testing, analysis, treatment and process equipment and other applications having similar or related requirements.

As will be discussed in a following more detailed description of the present invention, a typical diaphragm pump will include one or two pump heads, each of which includes a pump chamber with inlet and outlet valves and passages and a diaphragm reciprocally driven by a motor. A typical pump may have a single pump head or multiple pump heads, typically two pump heads with the diaphragms driven on opposing strokes of a common motor, but the pump heads will be essentially identical with the diaphragms being driven on corresponding stroke phases of a shared motor.

While the design and construction of diaphragm pumps are well developed and known, there are still persistent problems in the development of pumps having increased capacities or meeting requirements beyond those met by the current designs of pumps. For example, a current and recurring problem in diaphragm pump design is in designing and constructing pumps that are smaller than current pumps while still having capacities capable which meet reasonable requirements.

That is, and more specifically, one of the primary problems in developing smaller diaphragm pumps is that at least some of the necessary pump components are approaching a lower size limit because of any of a number of reasons. For example, in some instances the properties of the material comprising a component are dimension dependent such that the component cannot adequately perform it function when the dimensions of the component, and thus of the material comprising the component, fall below a certain physical size. This may occur, for example, when the thickness of a gasket becomes such that the compressibility of the gasket is insufficient to seal against the expected irregularities of the mating surfaces when the material is below a certain thickness.

In other instances, the manufacturing processes for a given material or the properties of the material may not allow the fabrication, or at least adequate fabrication, of components below a certain size. The lower limits on the reasonably realizable sizes of diaphragm pump components has, in turn, set an effective lower limit on the practicable sizes of diaphragm pumps.

The present invention provides a solution to these and related problems of the prior art.

SUMMARY OF THE INVENTION

The present invention is directed to diaphragm pump head with a non-resilient seal and to a diaphragm pump having at least one diaphragm pump head having a non-resilient seal.

According to the present invention, a diaphragm pump head includes a valve head and a valve cover that form a diaphragm chamber with a pump diaphragm forming at least a part of a wall of the diaphragm chamber. The valve cover includes an inlet passage leading from a pump input port and through an inlet valve to the diaphragm chamber and an outlet passage leading from the diaphragm chamber and through an outlet valve to a pump outlet port.

The inlet valve and the outlet valve each include a valve diaphragm and an inlet non-resilient seal and an outlet non-resilient seal wherein each non-resilient seal includes first and second annular diaphragm seating faces formed in mating faces of the valve body and the valve cover surrounding the inlet passage and the outlet passage and a non-resilient, deformable valve diaphragm encased or entrapped between the first and second diaphragm seating faces. In a present embodiment of the pump head, the inlet passage leads from the pump inlet port to an inlet side of the inlet valve and the outlet passage leads from an outlet side of the outlet valve to the pump outlet port and an outlet side of the inlet valve and an inlet side of the outlet valve are connected to the diaphragm chamber. In a present embodiment, the inlet valve opens in an inlet direction from the inlet passage to the diaphragm chamber and the outlet valve opens in an outlet direction from the diaphragm chamber to the outlet passage.

Further, according to the present invention, each valve diaphragm includes a central valve plate, a resiliently deformable valve spring surrounding the central valve plate and at least one but preferably a plurality of valve passages formed in the valve spring and surrounding the valve plate. In each non-resilient seal, the first annular diaphragm seating face is located on an inlet side of the valve and has a first valve passage with a first diameter less than a diameter of the central valve plate and the second annular diaphragm seating face is located on an outlet side of the pump and has a second valve passage with a second diameter greater than a diameter of the valve passages through the valve diaphragm.

The present invention also relates to a diaphragm pump head with a non-resilient seal, comprising: a valve head and a mating valve cover forming a diaphragm chamber, and a pump diaphragm forming at least a part of a wall of the diaphragm chamber, the valve cover including an inlet passage leading from a pump input port and through an inlet valve to the diaphragm chamber, and an outlet passage leading from the diaphragm chamber and through an outlet valve to a pump outlet port, wherein the inlet valve and the outlet valve each include a valve diaphragm, and an inlet non-resilient seal and an outlet non-resilient seal, each non-resilient seal including first and second annular diaphragm seating faces formed in mating faces of the valve body and the valve cover surrounding the inlet passage and the outlet passage and a non-resilient, deformable valve diaphragm entrapped between the first and second diaphragm seating faces.

BRIEF DESCRIPTION OF THE DRAWING(S)

The invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGS. 1A and 1B are diagrammatic representations of single. and double headed diaphragm pumps of the prior art;

FIGS. 1C, 1D, 1E and 1F are diagrammatic representations of the structure and operation of a diaphragm valve and seals of the prior art;

FIG. 2A is a diagrammatic representation of a diaphragm pump of the present invention with a non-resilient seal; and

FIG. 2B is a diagrammatic representation of a diaphragm valve plate of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A. Discussion of Diaphragm Pumps 10 of the Prior Art

Two forms of typical diaphragm pumps 10 of the prior art are illustrated in FIGS. 1A and 1B, a single head pump 10A and a dual head pump 10B. As shown, each pump 10 includes at least one pump head 12, indicated in FIG. 1B as pump heads 12 a and 12 b, and a motor 14 driving each pump head 12 through a corresponding connecting rod 16, respectively indicated in FIG. 1 b as connecting rods 16 a and 16 b, and pump heads 12 a and 12 b are normally identical to each other and are the same as pump head 12 in FIG. 1A.

Motor 14 is typically a rotating brushless electrical motor and drives connecting rod 16 or connecting rods 16 a and 16 b through an eccentric crank 18 driven by the shaft of motor 14. In the case of a single head pump 10A, connecting rod 16 is a simple rod connected at one end to eccentric crank 18 by a circular bearing and at the other end to a pump diaphragm 20 of the pump head 12, as will be discussed further below. In the case of a double head pump 10 b, connecting rods 16 a and 16 b are formed of the two arms of a yoke assembly, sometimes referred to as a “scotch yoke”, wherein each arm is connected to a corresponding pump diaphragm 20 and wherein the arms are centrally mounted to the eccentric crank 18 by a circular bearing.

Referring to FIG. 1 c, therein is shown a pump head 12 as may be employed in either of single head pump 10 a and a dual head pump 10 b. As shown, a pump head 12 typically includes valve body 22 and a valve cover 24 enclosing and forming a diaphragm chamber 26 therein, one side of which is formed of pump diaphragm 20.

In the present embodiment, valve cover 26 includes an inlet passage 26I leading to an inlet side 28I of an inlet valve 30 and an outlet passage 26O leading from an outlet side 32O of an outlet valve 34 while outlet side 28O of inlet valve 30 and the inlet side 32I of outlet valve 34 both open into and directly communicate with diaphragm chamber 26 of the pump head 12. Inlet valve 30 opens in the direction of arrow A from inlet passage 26I to diaphragm chamber 26 while output valve 34 opens in the direction of arrow B from diaphragm chamber 26 to outlet passage 28O, thereby providing a flow path from an inlet port 38I communicating with inlet passage 26I to an outlet port 38O communicating with outlet passage 26O.

During operation, pump diaphragm 20 is alternately driven towards and away from diaphragm chamber 26 by the reciprocating motion of connecting rod 16 coupled to motor 14, thus alternately and reciprocally reducing and increasing the internal volume of diaphragm chamber 26 and, by that reciprocal motion or action, alternately increasing and reducing the pressure within diaphragm chamber 26. Such operation of pump diaphragm 20 together with the one way operations of inlet valve 30 and outlet valve 34 will thereby result in a cyclical reduction in pressure, or suction, at inlet port 38I and an opposing cyclical increase in pressure at outlet port 38O, which may be used directly to move gas, liquid, fluid, etc. through the pump head 12.

Referring now to inlet valve 30 and outlet valve 34 and the surrounding structures of pump head 12 in further detail, it is shown in FIG. 1C that each of inlet valve 30 and outlet valve 34 includes a valve diaphragm 40. According to the present embodiment of the pump 10, as illustrated in FIGS. 1D, 1E and 1F, each valve diaphragm 40 typically comprises a circular membrane or diaphragm which forms a generally circular valve plate 42 and a surrounding resiliently deformable diaphragm forming a valve spring 44. A plurality of valve passages 46 are formed in the valve spring area of valve diaphragm 40 and around the valve plate area of valve diaphragm 40.

In the case of inlet valve 30, valve plate 42 is centered over the passage forming inlet side 28I of inlet valve 30, has a greater diameter than the passage forming inlet side 28I of inlet valve 30, and is normally biased against the opening of the passage forming inlet side 28I of inlet valve 30 by valve spring 44. In the case of outlet valve 34, valve plate 42 is centered over the passage forming the inlet side 32I of outlet valve 34, has a greater diameter than the passage forming the inlet side 32I of outlet valve 34 and is normally biased against the opening of the passage forming the inlet side 32I of outlet valve 34 by valve spring 44.

Inlet valve 30 and outlet valve 34 are therefore normally biased into their respective closed positions such that the valve plates 42 of their valve diaphragms 40 is biased against and blocking the input passages of inlet valve 30 and outlet valve 34. It will be noted that inlet valve 30 and outlet valve 34 will both also be biased into their closed positions at any time the pressure across either valve, due to the pressures in diaphragm chamber 26 and at inlet port 38I or outlet port 38O is in the reverse or opposite direction, that is, is against the intended direction of flow through the valves.

When the pressure across either of inlet valve 30 or outlet valve 34 is in the normal intended flow forward direction, however, that is, in the normal direction of flow through either of the valves, i.e., in the direction of arrows A and B, the respective valve spring 44 will allow the valve plate 42 and a surrounding area of the valve spring 44 with the valve passages 46 to bulge or deform away from the input passage of the valve and towards the outlet passage of the valve. This will, in turn, sufficiently displace the valve plate 42 away from the input passage of the valve in such a manner as to allow an intended flow of gas, liquid or fluid through the valve passages 46 from the input side of the valve to the outlet side of the valve.

Referring again to FIGS. 1C through 1F, it can be seen that each valve diaphragm 40 is supported on the inlet side of the valve, that is, on inlet side 28I of inlet valve 30 and on inlet side 32I of outlet valve 34, by a valve seat 48 that essentially extends the full width of valve diaphragm 40 with a central opening for the inlet passage of the valve. The valve seat 48 thereby provides the maximum support for the valve diaphragm 40 to reduce the possibility that the valve diaphragm 40 could be inverted by the operational pressure across the valve in the closed state. Valve seat 48 provides the primary seal between the valve diaphragm 40 and the body of the valve and, in particular, between the valve diaphragm 40 on the inlet side of the valve, and, for this reason, must be of sufficient thickness, resiliency and deformability to adapt and sealing conform to the mating surfaces of valve body 22 and valve cover 24.

It is also shown in FIGS. 1C-1F that on the output side of each valve, that is, outlet side 32O of outlet valve 34 and on outlet side 28O of inlet valve 30, the valve diaphragms 40 are supported around their circumferences by O-rings 50 that thereby support the valve diaphragms 40 in a suitable position against valve seats 48 and the inlet passages and seal the valve diaphragms 40 against the body of the valve. It must also be noted that by supporting the valve diaphragms 40 only around the circumferences of the valve diaphragms 40, the O-rings 50 allow the above described deformation of valve diaphragms 40 into the open position when the pressures across the valves so dictate. It must also be noted that because O-rings 50 provide the primary seal between the valve diaphragm 40 and the body of the valve on the outlet side of the valve, and, for this reason, must be of sufficient thickness, resiliency and deformability to adapt and conform to the mating surfaces of valve body 22 and valve cover 24 to prevent the leakage of any gas, liquid or fluid therebetween.

Lastly considering the materials from which a pump 10 may be constructed, the valve body 22 and a valve cover 24 are typically fabricated from metal or a cast or molded plastic material while diaphragm 20 is typically fabricated from a conventional flexible diaphragm material. Valve seat 48 and O-ring 50 are typically made of from conventional valve seat and O-ring materials, steel, rubber, etc.

B. Description of Diaphragm Pumps 52 According to the Present Invention

Referring again to the problems of the prior art that are addressed by the present invention, it must be noted that many of the elements of a pump 10 may be readily reduced in one or more dimensions while still retaining satisfactory performance from the pump 10. For example, there are well known methods for reducing the overall size of a motor 14, and the overall configuration and structure of a pump head 12 and of the passages through a pump head 12 may be readily re-configured or resized to reduce the overall size of the pump 10. In addition, many of the components of a pump 10, such as valve diaphragms 40 and pump diaphragms 20 are already relative small in at least one dimension and may typically be further reduced in size while still retaining adequate performance in the pump 10.

As discussed previously, pump 10 will commonly include certain elements that are effectively irreducible, such as valve seats 48 and O-rings 50, either because the material of the components cannot perform satisfactorily when reduced below a dimensional limit or sized dictated or determined by the material or because the fabricating processes will not allow the effective production of components of those materials of those dimensions at an acceptable price and yield rate. For example, it may not be feasible to mold valve seats or O-rings of the required thickness due to flow problems of the material in the molds or the integrity of the material.

Also, if the mating surfaces of the valve body or cover are not sufficiently parallel to one another or if the surfaces have local deformities, surface irregularities or roughness that is too great, the valve seats or O-rings may not have sufficient thickness so as conform to the mating surfaces in such a manner as to provide a reliable seal and/or operation of the valve. This may occur, for example, when the thickness of a gasket becomes such that the compressibility of the gasket is insufficient to effectively bridge the voids between the mating surfaces so as to seal against the irregularities of the mating surfaces. For example, if an O-ring has a thickness of 0.1 inch and can compress by fifty percent of its thickness, the O-ring may seal gaps between mating surfaces in the range of 0.05 inch to some distance less than 0.1 inch, such as 0.085 inch, depending upon the amount of compression pressure required to provide an adequate seal. If the expected gaps between the mating surfaces due to non-parallelism, roughness or local irregularities is in the range of 0.05 inch to 0.075 inch, then the O-ring would be able to provide an adequate seal. If, however, the O-ring has the same compressibility but is thinner, such as 0.8 inch, it may be able to seal gaps only in the range of 0.04 inch to 0.07 inch and may thus be unable to provide a reliable seal for greater surface irregularities.

For the above reasons, and according to the present invention, the next step in reducing the sizes of diaphragm pumps requires the reduction or elimination of either or both of valve seats 48 and O-rings 50.

According to the present invention, and as illustrated in FIG. 2A, a pump head 52 of a pump 54 of the present invention again includes a valve body 56 and a valve cover 58 enclosing and forming a diaphragm chamber 60 therein, one side of which is again formed or defined by a surface of a pump diaphragm 62.

Valve cover 58, as with the prior art design, includes an inlet passage 64I leading from inlet port 66I to an inlet side 68I of an inlet valve 70 and an outlet passage 64O leading from an outlet side 72O of an outlet valve 74 to an outlet port 66O and outlet side 68O of inlet valve 70 and the inlet side 72I of outlet valve 74 again open into valve chamber 76 of the pump head 52. As described above, inlet valve 70 opens in the direction from inlet passage 64I to diaphragm chamber 60 while outlet valve 74 opens in the direction from diaphragm chamber 60 to outlet passage 64O, thereby providing a flow path from an inlet port 66I to outlet port 66O.

As illustrated in FIGS. 2A and 2B, inlet valve 70 and outlet valve 74 again include a valve diaphragm 76 wherein each valve diaphragm 76 typically comprises a circular membrane or diaphragm forming a generally circular valve plate 78 and a surrounding resiliently deformable diaphragm forming a valve spring 80. As with the prior art design, a plurality of valve, passages 82 are formed in the valve spring area of valve diaphragm 76 and around the valve plate area of valve diaphragm 76.

It has been described herein above that a pump 54 of the present invention is reduced in size from a pump 10 of the prior art and, for this reason, the dimensions of valve body 56 and valve cover 58 and the passages and chambers therein are thereby reduced by about ¼ to about ⅓ from the corresponding dimensions of a pump 10 of the prior art. It will be recognized, however, that the dimensional changes need not be proportional with respect to either the corresponding dimensions of a pump 10 or relative with respect to the dimensions of related portions of the pump 54. For example, the designer make take advantage of the proportionate increase in the effective strength of some structural features when reduced in size to increase the relative size of other structural features. This may occur, for example, in the thickness of the walls of the inlet and outlet passages, in the diaphragm chamber and in the width or thickness of the pump diaphragm because the total pressure on these elements is reduced disproportionately as the surface area of the elements is reduced. It should also be noted that some overall dimensional reductions and internal dimensional increases or reductions may be made in the pump 54 by rearrangement of the structural elements of the pump 54.

According to the present invention, a further significant reduction in the dimensions of a pump 54 may be obtained by reducing the size, that is, the thickness, of valve seats 48 and O-rings 50, or by eliminating either or both of valve seats 48 and O-rings 50. As discussed, however, it has been found that a mere reduction in the dimensions of certain components, such as valve seats 48 and O-rings 50, is often not practical or effective due to material and fabrication limitations. That is, either the components do not perform their function adequately when their dimensions are reduced below some lower limit or the fabrication processes do not lend themselves to the effective fabrication of components having dimensions less than some lower limit.

According to the present invention, however, and as shown in FIGS. 2A and 2B, a reduction in the dimensions of a pump 54 compared to a pump 10 are achieved by completely eliminating the valve seats 48 and O-rings 50 in their entirety and instead employing a non-resilient seal 84 wherein the sealing function does not rely on the compressibility of a component comprising a resilient deformable material, such as a valve seat 48 or an O-ring 50.

As illustrated in FIG. 2 a, the pump 54 of the present invention does not include either valve seats 48 or O-rings 50 and the outer circumference of valve diaphragm 76, which in the case of diaphragm 20 is encased or entrapped between valve seat 48 and O-ring 50, is instead encased or entrapped between corresponding diaphragm seating faces 86 of valve body 56 and valve cover 58.

As shown in FIG. 2A, diaphragm seating face 86 a of inlet valve 70 forms an annular plane circumferentially surrounding inlet passage 64 i at the inlet side 68I of inlet valve 70 in the region previously occupied by a valve seat 48 while diaphragm seating face 86B for inlet valve 70 forms an annular plane circumferentially surrounding the outlet side 68O of inlet valve 70 in the region previously occupied by an O-ring 50. Diaphragm seating face 86C of outlet valve 74 forms an annular plane circumferentially surrounding outlet passage 64O at the inlet side 72I of outlet valve 74 in the region previously occupied by a valve seat 48 while diaphragm seating face 86D of outlet valve 74 forms an annular plane circumferentially surrounding the outlet passage 64O at outlet side 72O of outlet valve 74 in the region previously occupied by an O-ring 50.

The non-resilient seal 84 of the present invention is thereby formed between the valve diaphragm 76 and the diaphragm seating faces 86 and both forms the necessary seals between valve diaphragm 76, valve body 56 and valve cover 58 while also securing valve diaphragms 76 in place during operation of the pump 54. In a presently preferred embodiment of a non-resilient seal 84, diaphragm seating faces 86 are formed to a greater degree of parallelism and smoothness by machining diaphragm seating faces 86 rather than relying on the a casting or molding process to form the sealing faces, as in a pump 10 of the prior art. Typically, diaphragm seating faces 86 are machined to be a flat planar surface having a tolerance within ±0.025 inches and preferably or significantly less.

In addition, and while it is necessary that valve diaphragms 76 comprise a material that is sufficiently flexible and resilient to provide the valve spring 80 function, the non-resilient seal 84 does not necessarily require that the material of valve diaphragms 76 have the high degree of compressibility required by gaskets and O-rings of the prior art designs. A non-resilient seal 84 instead requires only that the material of valve diaphragms 76 be a slightly deformable material to conform to such non-parallelisms and dimensional variances as may remain, even with machined surfaces such as diaphragm seating faces 86, at the initial installation of the valve diaphragms 76 into the pump 54.

In an alternate embodiment of a non-resilient seal 84, the seal diaphragms 76 may comprise a material that becomes locally and temporarily softened by a locally applied solvent, for example. At assembly, those portions of seal diaphragms 76 forming the non-resilient seals 84 may be treated with the solvent to become locally softened during the assembly to thereby conform to diaphragm seating faces 86. After assembly, the material of seal diaphragms 76 would again harden, following evaporation of the solvent, and would thereby be ready for operation.

According to yet another embodiment of non-resilient seals 84, seal diaphragms 67 may comprise a material impregnated with an adhesive or sealant or of a material having a thin coating of adhesive or sealant, thereby providing the deformability desired for a complete seal, and perhaps also an adhesive property for greater strength and sealing, while retaining the desired reduction in the thickness of the seal diaphragm.

Finally, it will be recognized that valve body 56 and valve cover 58 may comprise a variety of materials so long as the materials are of sufficient strength for the operating pressures of the pump in the desired component thicknesses and so long as the material may be machined, ground or polished to form diaphragm seating faces 86. For example, suitable materials may include metals such as aluminum and various forms of plastics.

Lastly, in a typical embodiment of a pump 54, the dimensions are about 2.25 inches or so by about 2.25 inches or so by about 2.25 inches or so and preferably less. The motor, for driving the pump according to the present invention, is preferably a brushless motor which is generally manufactured in accordance with the teachings of one or more of U.S. Pat. Nos. 3,333,172, 3,377,537, 3,569,806, 3,587,670, 3,617,841, 3,665,259, 3,901,084, 4,077263 and 4,475,065 which teachings are herein incorporated by reference. One manufacture of a brushless motor, suitable for use with the present invention, is Brailsford & Company, Inc. of Antrim, N.H.

It will be recognized that because changes may be made in the above described invention without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention. 

1. A diaphragm pump head with a non-resilient seal, comprising: a valve head and a mating valve cover forming a diaphragm chamber, and a pump diaphragm forming at least a part of a wall of the diaphragm chamber, the valve cover including an inlet passage leading from a pump input port and through an inlet valve to the diaphragm chamber, and an outlet passage leading from the diaphragm chamber and through an outlet valve to a pump outlet port, wherein the inlet valve and the outlet valve each include a valve diaphragm, and an inlet non-resilient seal and an outlet non-resilient seal, each non-resilient seal including first and second annular diaphragm seating faces formed in mating faces of the valve body and the valve cover surrounding the inlet passage and the outlet passage and a non-resilient, deformable valve diaphragm entrapped between the first and second diaphragm seating faces.
 2. The diaphragm pump head of claim 1, wherein each valve diaphragm includes: a central valve plate, a resiliently deformable valve spring surrounding the central valve plate, and a plurality of valve passages formed in the valve spring and surrounding the valve plate.
 3. The diaphragm pump head of claim 1, wherein the inlet valve opens in an inlet direction from the inlet passage to the diaphragm chamber, and the outlet valve opens in an outlet direction from the diaphragm chamber to the outlet passage.
 4. The diaphragm pump head of claim 1, wherein the inlet passage leads from the pump inlet port to an inlet side of the inlet valve, the outlet passage leads from an outlet side of the outlet valve to the pump outlet port, an outlet side of the inlet valve and an inlet set of the outlet valve are connected to the diaphragm chamber.
 5. The diaphragm pump head of claim 1, wherein each valve diaphragm includes a central valve plate, a resiliently deformable valve spring surrounding the central valve plate, and a plurality of valve passages formed in the valve spring and surrounding the valve plate, and in each non-resilient seal, the first annular diaphragm seating face is located on an inlet side of the valve and has a first valve passage with a first diameter less than a diameter of the central valve plate, and the second annular diaphragm seating face is located on an outlet side of the pump and has a second valve passage with a second diameter greater than a diameter of the valve passages through the valve diaphragm.
 6. A diaphragm pump with a non-resilient seal, comprising: a valve head and a valve cover forming a diaphragm chamber, and a pump diaphragm forming at least a part of a wall of the diaphragm chamber, the valve cover including an inlet passage leading from a pump input port and through an inlet valve to the diaphragm chamber, and an outlet passage leading from the diaphragm chamber and through an outlet valve to a pump outlet port, wherein the inlet valve and the outlet valve each include a valve diaphragm, and an inlet non-resilient seal and an outlet non-resilient seal, each non-resilient seal including first and second annular diaphragm seating faces formed in mating faces of the valve body and the valve cover surrounding the inlet passage and the outlet passage and a non-resilient, deformable valve diaphragm entrapped between the first and second diaphragm seating faces, a motor driving an eccentric crank, and a connecting rod connected between the eccentric crank and the pump diaphragm of the at least one pump head and driven with a reciprocating motion by the eccentric crank.
 7. The diaphragm pump of claim 6, wherein each valve diaphragm includes: a central valve plate, a resiliently deformable valve spring surrounding the central valve plate, and a plurality of valve passages formed in the valve spring and surrounding the valve plate.
 8. The diaphragm pump head of claim 1, wherein the inlet valve opens in an inlet direction from the inlet passage to the diaphragm chamber, and the outlet valve opens in an outlet direction from the diaphragm chamber to the outlet passage.
 9. The diaphragm pump head of claim 6, wherein the inlet passage leads from the pump inlet port to an inlet side of the inlet valve, the outlet passage leads from an outlet side of the outlet valve to the pump outlet port, an outlet side of the inlet valve and an inlet set of the outlet valve are connected to the diaphragm chamber.
 10. The diaphragm pump head of claim 6, wherein each valve diaphragm includes a central valve plate, a resiliently deformable valve spring surrounding the central valve plate, and a plurality of valve passages formed in the valve spring and surrounding the valve plate, and in each non-resilient seal, the first annular diaphragm seating face is located on an inlet side of the valve and has a first valve passage with a first diameter less than a diameter of the central valve plate, and the second annular diaphragm seating face is located on an outlet side of the pump and has a second valve passage with a second diameter greater than a diameter of the valve passages through the valve diaphragm. 